Objectives: The aim was to determine the strength of signals derived from the dental pulp and those from the surrounding tissues in human teeth using the laser Doppler flowmetry (LDF). Methods: Twenty-six vital teeth (13 experimental and 13 controls) from 12 patients were used. Experimental teeth had root canal treatment in a single visit and their healthy antimeres were controls. Blood flow measurements were made before and after local anaesthesia, after root canal preparation, following root canal fitting and coronal restoration. Results: Perfusion unit (PU) values recorded from empty pulp chamber were determined to be only 30% tower than the values recorded before anaesthesia from the experimental. intact teeth. When the measurements in the group were compared with each other the values of variation in the both groups were not statisticatty significant. The variation between the groups when the measurement values before anaesthesia, 10 min after anaesthesia and after coronal restoration were compared, it was not statisticatty significant (P > 0.05). The variation between the groups after preparation and root canal fitting in their values of measurements was important statisticatty (P < 0.05). The measurement values of the study group were tower than that of the control group. Conclusions: In pulpal, LDF a major portion of the si. gnat comes from tissues other than pulp. Without taking precautions (such as rubber-dam application) in pulp blood flow measurements, the results may be inconsistent. (C) 2003 Elsevier Ltd. All rights reserved.